Military and commercial jet aircraft manufacturing techniques are well-known in the art. Crucial to such manufacture is the construction of the fuselage assembly, which is widely regarded as the most complex and costly aspect of aircraft construction, particularly in relation to the construction of large, commercial aircraft. Generally, such process includes making certain barrel and aft duct assemblies with additional substructure and installing subsystems thereonto. Ultimately, skin panels are fastened thereabout, typically by a multiplicity of rivets. With respect to the latter, it is widely recognized that such process is extremely costly and labor intensive due to the high quantity of fastener holes to be drilled in this particular section of the aircraft. In this regard, it is not uncommon for more than 1,500 fastener holes be drilled in order to attach the exterior skin components to only one side of the fuselage assembly of a single aircraft.
Additionally problematic with the construction of the fuselage assembly of such aircraft is the incorporation of interference-fit holes in a metal substructure forming the fuselage, and clearance-fit holes in the composite skin affixed thereto. In this regard, and unlike the majority of other fastener holes formed on aircraft, such bifurcated hole size system is deemed desirable insofar as weight savings can be substantially accomplished. Specifically, such two-step hole arrangement enables a lighter substructure to be utilized without compromising strength, due to the interference-fit holes, while preventing skin delamination, via the use of clearance-fit holes.
Notwithstanding the benefits of such design and resultant lightweight structure formed thereby, such assembly process has proven to be more difficult insofar as the skin components must be repeatedly removed from the structure so the clearance-fit holes formed thereon may be opened up by hand. Accurate skin location then becomes an issue as the skin is unloaded and reloaded on the assembly, making mechanization of such manufacturing process difficult to achieve.
Accordingly, there is a substantial need in the art for an assembly method, and in particular a systematic drilling method for use in the construction of fuselage assemblies that enables a multiplicity of fastener holes to be formed about the fuselage assembly in a simultaneous manner. There is an additional need in the art for such method that can simultaneously produce dissimilar-type holes, and in particular, interference-fit holes in the metal substructure of such fuselage assembly and clearance-fit holes in the composite skin to be attached thereto, continuously about such fuselage assembly in multiple planes. There is yet further a need in the art for such a method that can provide for such automated formation of fastener holes throughout a fuselage assembly that further includes quality assurance mechanisms to verify aircraft skin position and orientation relative the fuselage assembly when affixed thereto via such mechanized process.